Steam has been used in many different methods for the recovery of oil from subterranean, viscous oil-containing formations. The two most basic processes using steam for the recovery of oil includes a "steam drive" process and "huff and puff" steam processes. Steam drive involves injecting steam through an injection well into a formation. Upon entering the formation, the heat transferred to the formation by the steam lowers the viscosity of the formation oil, thereby improving its mobility. In addition, the continued injection of the steam provides the drive to displace the oil toward a production well from which it is produced. Huff and puff involes injecting steam into a formation through a well, stopping the injection of steam, permitting the formation to soak and then back producing oil through the original well.
Steam flooding operations for recovering heavy oil utilizing propane or diesel fired downhole steam generators are described in the articles "Steam Generators Work Long Periods Downhole", OIL AND GAS JOURNAL, July 5, 1982, pp. 76 and 78, and "West Coast For Project Results Discouraging", OIL AND GAS JOURNAL, Aug. 9, 1982, page 82.
The present invention provides an improved steam flood recovery process wherein steam is generated in a downhole generator located in the injection well adjacent the oil-containing formation by spontaneous combustion of a pressurized mixture of a water-soluble fuel dissolved in water or a hydrocarbon fuel-in-water emulsion with substantially pure oxygen.